Summer Stress Management Summary

At Grigg Brothers, we strive to generate and compile data into a set of actionable and easily executed practical solutions for turfgrass managers.

Leading into the 2015 growing season, we are providing our sum­mer stress management, and spe­cifically our “anthracnose” manage­ment story based on 10+ years of research data. We’re excited to of­fer up advice for turf managers that builds on our existing and effective nutritional Integrated Pest Manage­ment (IPM) strategies designed to maximize plant health, limit nutri­tional losses to the environment, reduce chemical inputs and save turf mangers money.

Plant Health – New Technology as a Tool

This is an exciting era for plant nutrition as we gain a better under­standing of plant nutrition, develop more efficient nutrient formulations and consider the use of “elicitors” (see Elicitors and Turfgrass Man­agement: Correct Use and Discov­ery www.gri.gg/bolo309 ) as a tool to further maximize plant health under environmental stress.

Grigg Brothers is considered by many as the leader in current elicitor research and effective integration into practical programs designed to manage turfgrass stress using PM. Our Proven Foliar fertilizer tech­nology provides chelated nutrient options which represent the most effective, efficient and safe nutrient source available to turf managers.

Phosphite Fate

An important and recent innova­tion includes the evaluation of phos­phite (H2PO3-) accumulation in plant tissue after treatment with PK-Plus (3-7-18 + 14% H2PO3-). This work demonstrated the systemic nature of H2PO3- once absorbed by leaf tissue and has led to the most ef­fective product application rate and timing recommendations. Phosphite accumulated in leaf tissue after the application of 0.35 g H2PO3- m-2 [6 fl. oz./1000 ft2 (M) PK-Plus] and reached its highest concentration (4,889 ppm) 48 hr after application (Figure1).

As expected, H2PO3- translo­cated to root tissue but was found in smaller concentrations—a range of 55-492 ppm. Based on field ob­servations, we estimate the need to maintain tissue H2PO3- concentra­tions ≥ 1,800 ppm (see dashed red

Not all phosphite fertilizers are created the same, and turf manag­ers should select products proven to get results. More than 10 years of research and field results verify that routine use of PK-Plus is an effec­tive stress and management tool that also provides mineral nutrition for better quality and more depend­able turf.

PK-Plus is the only foliar fertilizer scientifically documented as an ef­fective approach to managing the summer decline of cool and warm season grasses, including anthrac­nose (Collectotrichum cereale), mi­crodochium patch (Microdochium nivale), pythium (Pythium spp.), and root-knot nematodes.

Anthracnose Management

Our anthracnose ‘story’ is based on 10 years of research. Anthrac­nose (Colletotrichum cereale) has become a major disease problem on annual bluegrass (Poa annua) putting greens (Figure 2). An inte­grated approach remains essential to manage this disease effectively.

Initial research from 2003 indicated that the use of potassium phos­phite in the form of PK-Plus could lessen the severity of anthracnose compared to the fertilizer alone (Gary’s Green) and control treat­ments. Phosphite (H2PO3-) provides disease management options and plant health benefits that result from the upregulation of the turf’s natural defense mechanisms such as anti­oxidant production.

Recommendations

PK-Plus alone will provide some level of suppression but not acceptable.

A significant interaction between PK-Plus and contact fungicides occurs—compared to the sum of each individual part (PK-Plus or contact fungicide applied alone). Consistent research results document the synergy associated with repeat applications of 6 fl. oz./M of PK-Plus combined with 1.8 oz/M of Daconil Ultrex. This combination, even under severe disease pressure, provided excellent anthracnose suppression and equal to more elaborate fungicide programs.